A Spatially Distributed Water Balance based on Physical, Isotopic and Remotely Sensed Data

C. M. U. Neale
David G. Tarboton, Utah State University
J. J. McDonnell
T. Jackson
G. A. Artan
P. V. Unnikrishna

Final Report under USGS Contract 14-08-0001-G2110


A distributed mass balance approach is being developed to model spatially variable hydrologic processes in an arid mountain watershed. The model will be applied to Upper Sheep Creek, a 26 ha catchment within the Reynolds Creek ARS Experimental Watershed, near Boise, rD. The model is based on a DEM representation of basin topography. A mass balance equation relating moisture inflow, outflow, and the change in storage is resolved to give the moisture defecit in each DEM cell, Moisture input is subsurface flow from up-gradient DEM cells and surface infux from rain or a spatially distributed energy-balance snowmelt model. Subsurface outflow is determined from topographic slope and transmissivity, which is a function of moisture content. We illustrate the effects of topography on the areal distribution of soil moisture and the time variation of streamflow in Upper Sheep Creek and compare our results with field observations and streamflow measurements.